JP2711003B2 - Matrix type display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matrix type display device, and more particularly to an improvement in the yield of a thin film transistor (hereinafter, referred to as TFT) array substrate and a display device using the same. .

[Conventional technology]

Matrix type display devices are generally constructed by sandwiching a display material such as liquid crystal between two opposed substrates and applying a voltage to the display material. At this time, pixel electrodes arranged in a matrix are provided on at least one substrate, and an active element having a non-linear characteristic such as a TFT is provided for each pixel in order to selectively operate these pixels.

FIGS. 4 to 6 show a conventional apparatus of this type disclosed in Japanese Patent Application Laid-Open No. 63-221678. FIG. 4 is a partial plan view showing a conventional matrix type display device, and FIG.
The figure is a cross-sectional view taken along the line VV in FIG. 4, and FIG. 6 is a cross-sectional view of a part being manufactured.

In the figure, (1) is a transparent insulating substrate, (2) is a pixel electrode, (3) is a gate electrode and wiring, (4) is a gate insulating film, (5) is a semiconductor layer, and (6) is an etching stopper. , (7) is a source / drain ohmic contact layer, (8) is a source electrode / wiring, and (9) is a drain electrode. This liquid crystal display device will be described based on manufacturing steps. First, ITO (Indium Tin) was deposited on the cleaned transparent insulating substrate (1) by EB evaporation or sputtering.
Oxide) and the like. This is processed into a desired pattern by a method such as a photo-etching method to form a pixel electrode (2), an electrode terminal and the like. Secondly, a film of a high melting point metal such as Cr is formed by a sputtering method or the like, and a gate electrode and a wiring (3) are formed in the same manner. The third gate insulating film (4) as a SiO ₂ or SiN, a semiconductor layer (5) as a i-a-Si and poli-Si, and Etsu quenching Sutotsu per (6) as a continuous plasma CVD SiO ₂ or SiN of The film is formed by a method or the like. Fourth, a contact hole for source / drain contact is formed in the etching stopper (6), and after pre-treatment with a buffered hydrofluoric acid (BHF) solution or the like, a source / drain ohmic contact layer (7) is formed.
An n ⁺ -a-Si film is formed. Fifth, a contact hole for connecting the pixel electrode (2) and a drain electrode (9) to be formed later is formed. Sixth, Al ・ Al / Cr, Al / Mo or A
An alloy or the like is formed by a sputtering method or the like and patterned to form a source electrode / wiring (8) and a drain electrode (9). As described above, the TFT array substrate is formed. A counter electrode substrate provided with a transparent conductive film, a color filter, and the like is provided opposite to the TFT array substrate, and a liquid crystal surface display is formed by sandwiching a liquid crystal or the like between the two.

[Problems to be solved by the invention]

In the conventional matrix type display device, when forming the TFT array substrate as described above, before forming the fourth n ⁺ -a-Si (7) on the conventional device shown in FIG. Then, it is pre-treated with a BHF solution or the like to clean its surface. At this time, the film on the surface of the substrate exposed to this solution includes both SiN (or SiO ₂ ) as an etching stopper (6) and ia-Si (or Poli-Si) as a semiconductor layer (5). It is difficult to optimize the conditions when pre-treating such a substrate with a BHF solution, etc.
There was a problem when n ⁺ -a-Si (7) was peeled off.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the surface of a substrate to be pre-treated before forming a source / drain contact layer (7) is made of a single material as much as possible. Another object of the present invention is to simplify optimization of pretreatment conditions and improve the yield of this process.

[Means for solving the problem]

The matrix type display device according to the present invention has a structure having a second etching stopper made of substantially the same material as the semiconductor layer between the conventional first etching stopper and the source / drain contact layer. Things.

[Action]

The second etching stopper according to the present invention is formed of a material substantially the same as the material of the semiconductor layer, and in a BHF process performed after patterning of the etching stopper and before forming the source / drain contact layer, B
The substrate surface exposed to the HF solution is made of a single material, which facilitates optimization of the BHF treatment, and further improves the adhesion of the source / drain ohmic contact layers formed thereafter.

〔Example〕

1 to 3 show a matrix type display device according to an embodiment of the present invention. FIG. 1 is a partial plan view of the matrix type display device, and FIG. 2 is a sectional view taken along line II-II of FIG. FIG. 3 is a sectional view in the course of manufacture. 1 to 3, the same reference numerals as those in FIGS. 4 to 6 indicate the same or corresponding parts. Further, (10) is a second etching stopper, which will be described below based on its manufacturing process.

First, a film of ITO is formed on the transparent insulating substrate (1) by EB evaporation or sputtering, and this is patterned by photoetching or the like to form a pixel electrode (2) and an electrode terminal. Second, a film of a high melting point metal such as Cr is formed by a sputter method or the like, and pattern processing is performed to form a gate electrode / wiring (3) and the like. Third, SiN as gate insulating film (4)
Alternatively, SiO ₂ , ia-Si or poli-Si as a semiconductor layer (5), SiN or SiO _{2 as} a first etching stopper (6), and i- as a second etching stopper (10). a-Si or poli-Si is continuously formed by a plasma CVD method or the like. Fourth, source / drain contact holes are made in the first and second etching stoppers (6) and (10). After that, pre-treatment with BHF solution etc., source / drain automix contact layer (7)
Is formed as n ⁺ -a-Si. Fifth, a contact hole for connecting the pixel electrode (2) and the drain electrode (9) is formed. Sixth, Al, Al / Cr, Al / Mo, Al alloy, etc. are formed by sputtering or the like, and patterned by photoetching or the like, and source electrode / wiring (8)
And forming a drain electrode (9).

As described above, the TFT array substrate is formed. This TFT
A counter electrode substrate provided with a transparent conductive film and a color filter is provided opposite to the array substrate, and a display material such as liquid crystal is sandwiched between the two to form a liquid crystal flat display.

In the case of the above configuration, n ⁺ -a-Si as the fourth source / drain ohmic contact layer (7)
During the pretreatment immediately before film formation, the substrate surface is almost completely covered with the second etching stopper (10) as shown in FIG.
And the semiconductor layer (5) are covered with ia-Si (or poli-Si), so that the control of the pretreatment is facilitated and the margin is widened. As a result, the ohmic contact between n ⁺ -a-Si and ia-Si becomes excellent and uniform, and since n ⁺ -a-Si has never been peeled off, TF of high yield and high quality can be obtained.
T arrays can be provided.

 In addition, each material is not limited to the above embodiment.

〔The invention's effect〕

As described above, according to the present invention, a pixel electrode, a gate electrode, a gate insulating film, a semiconductor layer,
A first etching stopper, a source / drain contact layer, a thin film transistor (TFT) array substrate on which a source electrode / wiring and a drain electrode are sequentially placed, and a counter electrode substrate having a transparent electrode and a color filter;
In a matrix type display device having a display material sandwiched between a TFT array substrate and a counter electrode substrate, a material substantially the same as the material of the semiconductor layer is provided between the first etching stopper and the source / drain contact layer. With the structure having the second etching stopper according to the above, the adhesion between the source / drain contact layers can be improved, and a high yield and high quality matrix type display device can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view showing a main part of a TFT array substrate used in a matrix type display device according to one embodiment of the present invention,
FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1, FIG. 3 is a cross-sectional view during manufacturing, FIG. 4 is a plan view showing a main part of a TFT array substrate used in a conventional matrix type display device. FIG. 5 is a cross-sectional view taken along the line VV of FIG. 4, and FIG. 6 is a cross-sectional view in the course of manufacturing. (1) is a transparent insulating substrate, (2) is a pixel electrode, (3) is a gate electrode and wiring, (4) is a gate insulating film, (5) is a semiconductor layer, (6) is a first etching stopper, (7) is a source / drain contact layer, (8) is a source electrode /
Wiring, (9) is a drain electrode, and (10) is a second etching stopper. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] A thin film transistor in which a pixel electrode, a gate electrode, a gate insulating film, a semiconductor layer, a first etching stopper, a source / drain contact layer, a source electrode / wiring, and a drain electrode are sequentially mounted on a transparent insulating substrate. TF
T) A matrix type display device comprising an array substrate and a counter electrode substrate having a transparent electrode and a color filter, wherein a display material is sandwiched between the TFT array substrate and the counter electrode substrate. And a second etching stop made of a material substantially the same as the material of the semiconductor layer between the source and drain contact layers.